Full-length viral genomic RNA from Rauscher murine leukemia virus was translated in a mRNA-dependent cell-free protein synthesis system. The product include polypeptides of 200,000 and 65,000 apparent mol. wts. These polypeptides were found to be identical to intracellular authentic viral precursor polyproteins Pr200gag-pol and Pr65gag. Pr200gag-pol is a precursor polyprotein containing antigenic determinants of the four structural proteins p30, p15, p12 and p10 and viral reverse transcriptase (p80pol). Pr200gag-pol was found to be the initial translation product of the reverse transcriptase gene and is proposed to result from a translational control mechanism in which ribosomes frequently terminate at the end of the core protein gene but occassionally bypass this release point and continue on into the reverse transcriptase gene yielding Pr200gag-pol. The end result is that reverse transcriptase is formed at 1/20th to 1/10th the rate of the core proteins. The envelope proteins do not appear to be translated from full-length viral genomic RNA but instead are made from a intracellular viral mRNA of about 1/3rd the size of the viral genome. It probably only encodes the envelope proteins. Neither the core nor the reverse transcriptase gene is encoded in this mRNA. The initial gene product is a 68,000 mol. wt. precursor containing viral gp69/71 and p15E peptide sequences. It is termed Pr68env. It has an identical methionine-containing tryptic peptide pattern to that of authentic gPr90env, the glycosylated intracellular precursor to the two viral envelope proteins.